Free radical addition of isobutyric acid to α,ω-diolefins. A new route to α,α,α′,α′-tetramethylalkanedioic acids

Abstract

2,2,9,9-Tetramethylsebacic and 2,2,8,8-tetramethylazelaic acids have been synthesized in resonable yields (55% in the case of the former) by the free radical addition of isobutyric acid to hexa-1,5-diene and penta-1,4-diene respectively using di-t-butyl peroxide as initiator. Extension of this method to hepta-1,6-diene and octa-1,7-diene led to the production of new cyclic compounds. cis- and trans-2,2-Dimethyl-3-(2-methylcyclopentyl)propionic acids were obtained from hepta-1,6-diene and cis- and trans-2,2-dimethyl-3-(2-methylcyclohexyl)propionic acids and 2,2-dimethyl-3-cycloheptylpropionic acid from octa-1,7-diene. The mechanisms of these reactions are discussed. Some attempted additions of isobutyric acid to methylene cycloalkanes containing five-, six-, and seven-membered rings are described.